1. Field of the Invention
The present invention pertains to a pressure plate assembly for a friction clutch, comprising a housing arrangement designed to be connected to a flywheel arrangement; a pressure plate mounted in the housing arrangement so that it can move axially; a stored-energy element; a wear-compensating device acting in the path of force transmission between the stored-energy element and the pressure plate, where the wear-compensating device has at least one adjusting element which can move in an adjusting direction to compensate for wear; and at least one clearance-producing arrangement, comprising a gripping element on the pressure plate, which, on the occurrence of wear, comes or can be brought to rest against a blocking element fixed in position relative to the housing arrangement.
2. Description of the Related Art
A pressure plate assembly of this type is known, for example, from U.S. Pat. No. 6,123,180. In this known pressure plate assembly, the blocking element provided to cooperate with the gripping element of the clearance-producing arrangement is screwed to the housing arrangement with threaded bolts and thus connected tightly to it. For this purpose, the housing arrangement has an elevated part with a surface which is intended to face the flywheel arrangement, on which surface a corresponding surface of the blocking element rests when the screwed connection mentioned above is made. As a result of this design, it is necessary to connect the blocking element tightly to the housing arrangement before the pressure plate and the components working together or associated with it are assembled to form the pressure plate assembly. This leads to the problem that, after the assembly comprising the housing arrangement and the blocking element and the assembly comprising the pressure plate, the wear-compensating device, and the clearance-producing arrangement have been put together, the pretensioning force provided by the stored-energy element acting between the housing arrangement and the pressure plate and the fact that the pressure plate assembly has not yet been connected to the flywheel arrangement, which means that there is no support for the pressure plate, lead to the potential danger of an interaction between the blocking element and the gripping element of the clearance-producing arrangement. Such an interaction would bring about an unwanted wear-compensating adjustment, even though no wear at all had occurred. The pressure plate assembly would thus ultimately arrive in a state in which it could no longer be attached to a flywheel arrangement to form a friction clutch. In pressure plate assemblies of this type, it is therefore a known and practiced technique to use some sort of transport securing devices to ensure that the pressure plate is held in a position shifted toward the housing arrangement. At the same time, the stored-energy element is put under tension to avoid the undesirable interaction described above between the gripping element and the blocking element. Providing transport securing devices to keep the stored-energy element in a highly pretensioned position, however, is a complicated matter, especially in view of the fact that the transport securing devices must be designed with enough strength and solidity and installed with sufficient permanence to ensure that the stored-energy element, which usually produces a comparatively large amount of force, can be held in the preloaded state noted above.
It is the object of the present invention to provide simple measures for preventing the wear-compensating device of a pressure plate assembly from making an unwanted wear-compensating adjustment before the pressure plate assembly is put together with a flywheel arrangement.
According to the invention, when the housing arrangement is connected to the flywheel arrangement, the blocking element arrives in a state in which it is able to enter into a blocking interaction with the associated gripping elements.
Because the process of putting together the housing arrangement and the flywheel arrangement of the pressure plate assembly according to the invention brings the blocking element necessarily into the final position intended for it and thus into the position in which it is able to act as a blocker, the assembly process is greatly simplified, and at the same time it is ensured that the blocking element is kept in a passive state before this assembly process is carried out, which means that it is impossible for an undesirable adjusting movement of the wear-compensating device to occur. With a pressure plate assembly according to the invention, therefore, there is no need to take complicated transport-securing measures to ensure that the pressure plate is pulled back far enough into the housing arrangement against the very highly pretensioned state of the stored-energy element. With the blocking element already in its final position relative to the housing arrangement, the previously explained blocking interaction between the blocking element and the gripping element cannot occur in the secured-for-transport state.
In the pressure plate assembly according to the invention, a support element, for example, can be provided, by means of which the blocking element is supported on the housing arrangement in such a way that, before the pressure plate assembly is connected to the flywheel arrangement, the blocking element is kept in a state in which it is unable to enter into a blocking interaction with the associated gripping element. It can also be provided that the blocking element is carried by the support element in an area near the edge of the housing arrangement which is to be positioned in contact with the flywheel arrangement.
So that the blocking element can easily make the transition to the state in which it is able to interact, it is proposed that it be possible for the support element with the blocking element mounted on it to shift approximately in the same direction as that of the rotational axis during the process in which the housing arrangement is connected to the flywheel arrangement.
The design of the pressure plate assembly according to the invention can be simplified even more by allowing the blocking element to be held in position by the clamping action between the housing arrangement and the flywheel arrangement after the housing arrangement has been connected to the flywheel arrangement, because no additional components are then required to hold the blocking element in position.
In an alternative design, it can be provided that the support element is connected detachably to the blocking element on one side and also to the housing arrangement on the other side, and that the support element holds the blocking element in a predetermined position relative to the housing arrangement, which position, however, can be changed by the action of a force exerted during the process of connecting the housing arrangement to the flywheel arrangement. Because the support element is also connected detachably to the blocking element and thus can be removed after the pressure plate assembly has been connected to the flywheel arrangement, the danger that a support element of this type could cause the flywheel arrangement or the friction clutch attached to it to become out of balance is eliminated. In a design of this type, furthermore, it is possible to provide a displacement element, which, as the housing arrangement is being connected to the flywheel arrangement, moves the blocking element into a position where it can function as a blocker. It is possible for the displacement element to be permanently connected to the blocking element, and it can be provided with a contact area with which it cooperates with the flywheel arrangement to displace the blocking element.
So that the blocking element can be held securely in a defined position in the completely assembled state as well, it is proposed that, after the housing arrangement has been connected to the flywheel arrangement, a fastening bolt be inserted through the blocking element and the displacement element, and that the blocking element be clamped together with the displacement element between the housing arrangement and the flywheel arrangement.
The invention also pertains to a friction clutch which has a pressure plate assembly according to the invention.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.